The background art discloses prior formulations of rubbers for use in the rubber industry.
The background art shows use of Kraton in a number of rubber formulations. In U.S. Pat. No. 4,010,128 issued to Saggese et al. on Mar. 1, 1971 is disclosed use of Kraton rubber in printing plates. U.S. Pat. No. 3,507,934 issued to Minor et al. on Apr. 21, 1970 discloses the basic composition and method of manufacture for Kraton rubbers having a general form of an A-B-A block copolymer.
The incorporation of stearic acid into thermoplastic rubber compositions is taught in U.S. Pat. No. 4,010,128 issued to Saggese et al. on Mar. 1, 1977. Saggese et al. discloses mixing up to 10% by weight stearic acid with thermoplastic polymers including Kraton rubbers.
The use of stearic acid in combination with thermoset rubbers is taught in U.S. Pat. No. 3,882,062 issued to Aron on May 6, 1975 where up to 2% by weight stearic acid is mixed with natural rubbers. U.S. Pat. No. 4,039,506 issued to Gessler et al. on Aug. 2, 1977 teaches the use of up to 1% by weight stearic acid with thermoset rubber compositions. U.S. Pat. No. 4,046,834 issued to Lee et al. on Sept. 6, 1977 discloses use of up to 2% stearic acid with finely divided vulcanized rubber having a composition of approximately 90% styrene butadiene rubber. U.S. Pat. No. 2,638,460 issued to Couch on May 12, 1953 discloses use of up to 2% stearic acid with butadiene-styrene thermoset rubbers.